You can use the Active Coordinate Editor under the MSpoints menu. Just highlight the points you need to shift then shift them vertically;
You can use the RTS (Rotate, Translate, Scale) command;
Or you can edit the elevation of your initial traverse station and re-run the traverse.
You can use the same methods for a horizonal shift as well.

Save the file before doing any of them in case things go astray. Leaving a group of points behind is difficult to recover from.